Wastewater flows through the sewage piping in the underground, and the piping is disposed nearly horizontal and connected with a manhole, although the piping lies somewhat inclined to let water flow down.
In order to connect the piping with the manhole, the so-called flexible joint is used, which can absorb vibrations by earthquake or passing of vehicles, stratum change by earthquake, or offsets between the position of side hole drilled on the manhole and the position of the piping laid.
FIG. 5 shows one of conventional embodiments with a flexible joint 43. This flexible joint 43 has normally straight or tapered cylindrical form made of rubber. One end of the joint is fixed over the outside of the sewage piping 40 with a fixing ring 44, and another end is fixed with another kind of fixing ring 45 from inside of the flexible joint 43, after the piping is inserted into the side hole 42 of a manhole 41. The latter fixing ring 45 is normally annular strip material and fixes joints through expanding the fixing ring from inside. Thereby the clearance between the flexible joint 43 and the inner surface of a side hole 42 on the manhole 41 is shut, and the sealing of connecting position is ensured. It is on safety aspect functionally required for the connecting position that water may not leak not only at horizontal position but also at inclined or offset position of the piping 40 under hydraulic pressure of 1013 hPa.
It is possible not at construction site through pre-mounting to connect a flexible joint 43 onto the outer diameter of piping 40. And even if mounting should be done at construction site, there is so much space around the outside of joints 43 that mounting is easy and simply.
However in order to mount and fix the flexible joint 43 in the bore of side hole 42 on a manhole 41, the flexible ring 45 must be mounted and fixed from inside of a manhole, whereby the inner diameter of piping 40 is small as 30 cm for example as the case may be, then the use of tolls and the process of mounting is considerably restricted. Additionally the inside of a fixing ring 45 may not have large projection in respect to water flow and damage of rubber joint. Thereby it is required that the fixing ring is compact, mountable also in narrow space and sure not to cause water leakage.
In respect to fixing rings 45, many types of rings are proposed (for example see Japanese Patent Public Disclosures [KOKAI] No. 11-13078, 10-195900 and 9-144043). FIG. 6 shows one of them. In this case, the diameter of an annular strip material is enlarged through expanding the space between both ends 50a, 50b by using proper tools, and a spacer 51 is inserted into the space to keep the expanded diameter.
This type has simple construction, however must have many different spacers 51 corresponding to diameters. In order to accommodate to the real diameter of machined side holes 42 of a manhole, plurality of spacers 51 may have to be used in combination. Additionally it must be mounted with tools within narrow space in a flexible joint, so the combined spacers 51 cannot be easily inserted into narrow space.
FIG. 7 shows another one of conventional arts. In this type, both ends of metal fittings 56, which has V-form and is free extensible, are inserted or welded between both ends 55a, 55b of annular strip material 55. On mounting, this fixing ring 55 is set on the point to be fixed inside the flexible joint, and tools like jack, which expands the fixing ring, are placed between the peak of metal fitting 56 and the opposite point of 180°, and it extends the distance. The metal fitting 56 is crashed through extending the diameter and the circumference is enlarged. The fixing ring 55 is forced onto the inner surface of a flexible joint and fixes it.
This method has merit that it consists of a few components, but it cannot accommodate the dimension difference of side holes. Namely, tools are wearing, every time the side holes 42 are machined, and the inner diameter of side holes becomes smaller corresponding to the tool diameter. So at first it is required to machine the hole in largest dimension, thereby difference of fitting occurs between the largest and smallest diameter of side holes 42. And it can be only used in one nominal dimension. Though nominal dimension changes a little bit, many fixing rings 55 of different dimensions have to be stocked.
FIG. 8 shows also another one of embodiments according to conventional arts. The embodiment comprises two tapered slide of the expanded portion 63, 64. Namely, on both ends 60a, 60b of the annular fixing ring 60, two tapered slide 63, 64 are provided, two faces of which opposite to each other are wedge-formed. Tapered spacers 61, 62 with the same angle are disposed between them.
The tapered spacers 61, 62 come closer to each other through tightening the screws penetrating the tapered spacers 61, 62, then both ends 60a, 60b with tapered slides 63, 64 are pushed out to the opposite side and the flexible ring is fixed.
This method is more complex as the fore-mentioned method, but has merit that the both ends 60a, 60b of a fixing ring 60 can be expanded stepless.
However the axial dimension of expanding portion becomes larger, and the dimension range to be adjusted is also limited, nevertheless it is called as stepless.
Accordingly, the object of the present invention is to provide a fixing ring, which not only has compact form and structure but also can be adjusted stepless and fixed through wide range.